In Canada, 6 (21.4%) out of 28 women with early-onset BC (diagnosed < 30 years) and a positive family history of cancer were found to carry pathogenic TP53 variants—c.708C > A, IVS03-11C > G, c.524G > A, c.818G > A, c.743G > A). This evidence concerns the gene TP53 and breast cancer.